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Poly(propylene carbonate phthalate) (PPC-P) is a chemically modified poly(propylene carbonate) (PPC) biodegradable thermoplastic by introducing phthalic anhydride (PA) as the third monomer into the copolymerization of propylene oxide (PO) and CO2. To enhance the thermal and mechanical properties of PPC-P, a branching agent pyromellitic anhydride (PMDA) was introduced into the terpolymerization of PO, PA and CO2. The resulting copolymers with branched structure, named branched PPC-P, can be obtained using metal-free Lewis pair consisting of triethyl borane (TEB) and bis(triphenylphosphine)iminium chloride (PPNCl) as catalyst. The products obtained were analyzed by NMR spectroscopy and their thermal, mechanical properties and melt processability were evaluated by DSC, TGA, tensile test and melt flow index (MFI) measurement. The obtained branched PPC-P has a high molecular weight up to 156.0 kg·mol−1. It shows an increased glass transition temperature (Tg) higher than 50 °C and an enhanced tensile strength as high as 38.9 MPa. Noteworthily, the MFI value decreases obviously, indicative of an improved melt strength arising from the branched structure and high molecular weight. What is more, the branched PPC-P exhibits reasonable biodegradability, which demonstrates the great potential as a new green thermoplastic for the family of biodegradable plastics. [ABSTRACT FROM AUTHOR]

A series of semi-aromatic polyesters named as Poly(PO-CHO-PA) were facilely synthesized via ring-opening terpolymerization of bio-based cyclohexane oxide (CHO)/propylene oxide (PO)/phthalic anhydride (PA) using economical U1/PPNCl as dual catalyst. The proportion of CHO-PA and PO-PA segments in polymer can be readily altered by changing the feed ratio of CHO/PO because the reactivity ratios of CHO and PO with PA calculated by Fineman-Ross method are comparable. All synthesized amorphous polyesters with various compositions show one Tg ranging from 62 °C to 133 °C. Significantly, the mechanical, thermal and barrier properties of these amorphous semi-aromatic polyesters are also adjustable and investigated for the first time. The results indicate the semi-polyesters exhibit superior thermostability (T5% ranging from 306 °C to 323 °C) and high tensile strength (40.21–55.7 MPa) that is comparable with polystyrene (PS). Furthermore, Poly(PO-CHO-PA) films possess a promising prospect as packaging materials because of its colorless and highly transparent nature, along with low oxygen and water vapor transmission rate. All above performances may guarantee its potential alternative to commercial PS. [ABSTRACT FROM AUTHOR]

Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides (LDHs) were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH (OLDH) in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A series of poly(propylene carbonate) (PPC)/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient (OP) and water vapor permeability coefficient (WVP) is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics. [ABSTRACT FROM AUTHOR]

Using supported multi-component zinc dicarboxylate catalyst, poly(1,2-propylene carbonate- co-1,2-cyclohexylene carbonate) (PPCHC) was successfully synthesized from carbon dioxide (CO) with propylene oxide (PO) and cyclohexene oxide (CHO). The conversion of epoxides dramatically increased up to 89.7% (yield: 384.2 g of polymer per g of Zn) with increasing reaction temperature from 60°C to 80°C. The optimized reaction temperature is 80°C. The chemical structure, the molecular weight, as well as thermal and mechanical properties of the resulting terpolymers were investigated extensively. When CHO feed content (mol%) is lower than 10%, the PPCHC terpolymers have number average molecular weight ( M) ranging from 102 × 10 to 202 × 10 and molecular weight distribution (MWD) values ranging from 2.8 to 3.5. In contrast to poly(propylene carbonate) (PPC), the introduction of small amount of CHO leads to increase in the glass transition temperature from 38.0°C to 42.6°C. Similarly, the mechanical strength of the synthesized terpolymer is greatly enhanced due to the incorporation of CHO. These improvements in mechanical and thermal properties are of importance for the practical application of PPC. [ABSTRACT FROM AUTHOR]